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51.
本文用三级相互作用近似理论导出了高分子链末端距的四次矩的计算公式。计算聚亚甲基链的末端距四次矩,并同二级相互作用的结果进行了比较。对于聚亚甲基链,三级相互作用近似的四次矩小于二级相互作用近似的四次矩。 相似文献
52.
Angelika Baranowska Magdalena Siedlecka Andrzej J. Sadlej 《Theoretical chemistry accounts》2007,118(5-6):959-972
Recent studies of the perturbation-dependent basis sets have indicated the possibility of a significant reduction of the size
of the usual CGTO sets without considerable loss of accuracy in calculations of molecular electric properties. The resulting
(ZPolX) basis sets have been developed for several atoms of the first and second row of the Periodic Table. The same method
of the ZPolX basis set generation is extended for the first-row transition metals and the corresponding contracted ZPolX basis
sets of the size [6s5p3d1f] are determined for both nonrelativistic and scalar relativistic calculations. The performance
of the ZPolX basis sets is verified in calculations on the first-row transition metal oxides at the level of the ROHF, ROHF/CASPT2,
and ROHF/CCSD(T) approximations. Also the study of the dipole polarizability of TiCl4 confirms the excellent features of these very compact basis sets. The ZPolX basis sets for nonrelativistic and relativistic
calculations of molecular electric properties are available on the web page http://www.chem.uni.torun.pl/zchk/basis-sets.html. 相似文献
53.
V. Ya. Kavun N. F. Uvarov A. B. Slobodyuk V. K. Goncharuk A. Yu. Kotenkov I. A. Tkachenko A. V. Gerasimenko V. I. Sergienko 《Russian Journal of Electrochemistry》2005,41(5):501-509
Methods of (19F, 1H) NMR and impedance spectroscopy are used to investigate the internal mobility and ionic conduction in solid solutions arising in the system PbF2-ZrF4 and polycrystals KSnZrF7, Li(Na)(NH4)6Zr4F23, and M2ZrF6 (M = K, NH4). Factors responsible for the form of ionic motions and their energetics at 170–550 K are considered. It is established that the phase transitions in these compounds are connected with the crystal transition to a superionic state and that the high ionic (superionic) conductivity of beta phases is due to the diffusion of fluoride ions, ammonium cations, and possibly alkali metal cations. The obtained data testify to a substantial role of chainlike aggregation of anionic groupings and a variableness of structural mechanisms of formation of such chains in fluorozirconates for the development of translational diffusion in these compounds.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 573–582.Original Russian Text Copyright © 2005 by Kavun, Uvarov, Slobodyuk, Goncharuk, Kotenkov, Tkachenko, Gerasimenko, Sergienko. 相似文献
54.
The dipole moments of 2-alkylaminoand 2-alkylnitramino-3(or 5)-methyl-4-nitropyridines and their N-oxides have been measured, as well as calculated, using vectorial summation of the group moments and by ab initio method. The estimated interaction dipole moments, int, have been discussed in terms of the electronic and steric effects and intramolecular hydrogen bonding. Introduction of the NHCH3 group to position 2 in 4-nitropyridine strengthens the conjugation between the nitro group and ring nitrogen. The lack of such strengthening in 4-nitropyridine-N-oxides is explained as being due to formation of intramolecular hydrogen bond between the N-oxide group and the hydrogen of alkylamino group. Introduction of the nitramino group does not lead to marked modification of the charge distribution in a molecule. This fact may be explained by much weaker electron-donating ability of this group in comparison with the alkylamino group. 相似文献
55.
The main purpose of this paper is to present accurate infrared integrated intensities of liquid toluene, C6H5CH3, at 25 °C. Also presented are the decadic molar absorption coefficients, Em, the real and imaginary dielectric constants, ε′ and ε″, and the real and imaginary molar polarizabilities, ′m and ″m. Integrated intensities were determined as Cj, the area under bands in the spectrum, for all bands between 4800 and 440 cm−1. The contributions from the different bands were separated by fitting the spectrum with classical damped harmonic oscillator bands. The uncertainties in the integrated intensities of most bands are estimated to be 5–10%, with the uncertainties in very weak bands and in shoulders possibly up to 100%. The intensity that should be assigned to the fundamentals is more difficult to estimate due to Fermi resonance with overtone and combination bands, and a best estimate is given. The integrated intensities of the fundamental vibrations and the corresponding transition dipole moments are summarized and are compared with literature values for the gas. 相似文献
56.
采用B3LYP/6-31G*方法,对内含式化合物X@B12P12(X=Li0/+、Na0/+、K0/+、Be0/2+、Mg0/2+、Ca0/2+、H和He)的不同对称性构型进行了计算,讨论其最稳定构型的几何参数、布居分析、偶极矩、电离势、包含能、振动频率、能隙和自旋密度. 发现在X@B12P12化合物中,客体X=Li、Na0/+、K0/+、Mg0/2+、Ca0/2+和He处在偏离笼的中心0.006 nm的半径内. Be2+沿着C3轴偏离中心点0.279 nm. 在Be@B12P12和H@B12P12的基态结构中,Be和H与笼上的B原子成键. 除Li@B12P12、 Be2+@B12P12和He@ B12P12外, 其余结构为Cs对称稳定构型. 相似文献
57.
Dipole moments for,-dibromoalkanes containing 10, 12, 14, 18, 20 and 24 carbon atoms were determined in benzene solution at 25.00±0.05 °C. The experimental values of the dipole moments were found to compare well with the theoretical values calculated from Hayman and Eliezer's theory. 相似文献
58.
A simple detection method to observe the uniplanar orientation behavior of native cellulose microfibrils to the cell wall surface by using Fourier transform infrared (FTIR) spectroscopy in the transmission mode is reported. Four bands at 1372, 1355, 1337, and 1317 cm−1 (the latter two have been mentioned previously by Liang and Marchessault (1960, J. Polym. Sci. 43: 85–100)) were found to be sensitive to such orientation: the two middle bands at 1355 and 1337 cm−1 increase remarkably when the 0.60–61 nm lattice planes lie parallel to the cell wall surfaces. The reverse was true when the 0.53–54 nm lattice planes oriented preferentially. Polarization of the two bands at 1372 and 1355 cm−1 was parallel, while that of the other two bands at lower wavenumbers, i.e., at 1337 and 1317 cm−1, was perpendicular to the molecular axis of cellulose. These bands were assigned to OH-related motion, probably to in-plane OH bending, as reported by Maréchal and Chanzy (2000, J. Mol. Spectrosc. 523: 183–196). 相似文献
59.
First, we evaluated the complete electric dipole moment matrixeZ using a multi- AO basis on Cr, C, and O centers fortheimportant, parent organometallic molecule -C6H6Cr(CO)3. Second, we generated ground state LCAO-MO eigenvectors employing five commonly used semi-empirical procedures for molecules of this size which contain transition metals. Transformation of operator matrixeZ into the MO space of each of the five methods then leads us to conclude that the empirical input of Basch, Viste and Gray is most suitable. Finally, we compare the merits of several single- basis orbitals with the multi- metal orbitals.[/p] 相似文献
60.